Interest calculating machine



March 19, 1940. E. L. TURNBAUGH I INTEREST CALCULATING MACHINE FiledOct. 10, 1936 4 Sheets-Sheet 1 QNN E. L. 7urmawafi.

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March 19, 1940. E. L. TURNB AUGH INTEREST CALCULATING MACHINE Filed Oct.10, 1936 4 Sheets-Sheet 2 March 19, 1940. E, TURNBAUGH 2,193,848

INTEREST CALCULATING MACHINE Filed Oct. 10, 1936 I 4 Sheets-Sheet 3 51mm5''. L. Turrbbaafi.

March 19, 1940.

Filed 001:. 10, 1956 4 Sheets-Sheet 4 Patented Mar. 19, 1940 UNITEDSTATES PATENT- OFFICE INTEREST CALCULATING MACHINE Elbert L. Turnbau gh,San Francisco, Calif.

Application October 10, 1936, Serial No. 105,121

4 Claims.

This invention relates to an improved date finding unit for use withcalculating machines.

One object of the invention is to provide a date finding unit for usewith a machine of compact structure which may be conveniently used inbanks and other institutions and by means of which the basic amount ofinterest on one dollar can be quickly ascertained for any length of timeup to thecapacity of the machine. Another object of the invention is toprovide a machine of this character including mechanism for quicklycomputing the number of days intervening between any two given dates. Astill further object of the invention is to provide an improved interestcalculator of the above character which is durable and efficient in use,easy to manufacture, and one which can be placed upon the market at areasonable cost. The machine illustrated in the accompanying drawings isconstructed on a 365 day percentage unit basis and any number ofpercentage units can be installed.

In the accompanying drawings: Figure l is a top plan view of themachine. .25 Figure 2 is a top plan view of the machine with face platesremoved.

Figure 3 is a sectional view taken along the line 33 of Figure 2.

Figure 4 is a sectional view taken along the line 4-4 of Figure 2.

Figure 5 is a longitudinal sectional view of the date finding unit.

In order to accurately calculate the amount of interest due on a note,there has been provided a date finder unit which may be set to indicatethe starting date of the note, this being the date when the note wassigned. This date finder unit is set to indicate the starting date ofthe note and, during operation of the machine, gradually progresses fromthe date of the month the note was signed until the day is reached whenpayment is made, at which time operation of the machine will be broughtto a stop. The date finder unit is illustrated in Fig- 45 ures 1, 2 and3, and referring to these figures it will be seen that it has a frameincluding side plates or Walls I05 and I0! rising from a base H18 and attheir upper ends supporting the face plate 80. This face plate BI! is ofsuilicient size 50 to cover the date finder unit as well as the daycounter unit and in addition to the sight opening or window 89 is alsoformed with sight openings or windows I09 and H0. These sight openingsI09 and I It are in the form of slots extend- 55 ing transversely of theface plate and of such length that upon the upper or outer face of theface plate may be marked the names of the months, as shown at III. Ashaft H2 is rotatably mounted between the side walls I06 and I01 andcarries a gear H3 meshing with the gear 5 IM so that when the shaft 4 isturned by means of the crank I, rotary motion will be transmitted fromthe shaft 4 to gear H4 and in turn to the gear H3. In view of the factthat the gear H3 is free on the shaft H2, it may be rotated in- '10dependent of the shaft but as a pawl H5 is carried by the gear H3 and isyieldably held in engagement with a ratchet wheel lit by a spring I I7,the ratchet wheel will be turned with the gear II3 when this gear isturning in one direc- 15 tion and the shaft H2 to which the ratchet ispinned or otherwise rigidly secured will be turned in this directionwith the gear. The shaft II2 also carries a gear I I8 which is fixedupon an end portion of the shaft projecting from the side v2 wall I I)?and meshes with a gear H9 provided with a turning knob I20. It will thusbe seen that rotary motion may be transmitted to the shaft II2 eitherfrom the shaft 4 or by turning the knob I20. Twelve discs I2I, one foreach r month, are mounted upon the shaft H2 and each has upon itsperipheral edge face numbers corresponding to the number of days in themonth below which the disc appears through the sight opening III At oneside of each of these discs I2I is secured a gear I22 which has 62 teethand meshes with a gear I23 carried by a shaft I24 supported between theend walls of the frame, and referring to Figure 3 it will be seen thateach gear I23 has secured against a side face thereof a plate I25 formedwith a finger I26 for operating a Geneva wheel I21. The Geneva wheelsare mounted upon a shaft I28 supported between the side walls of theframe and against a side of each Geneva wheel is secured a gear I29meshing with a gear I30. Each of the gears I38 is secured against a sideof a disc I3I carried by a shaft I32. The discs itl correspond in numberto the discs IN and are disposed opposite these discs so that the discs.45 I3I show through the sight opening or window I09 above the names ofthe months, as shown in Figure 1. Upon each of the discs I3I is marked aletter K, and upon referring to Figure 2 it will be seen that theletters upon the twelve discs '50 are in such relation .to each otherthat they extend in a spiral path. Therefore, when the discs I2! arerotated and rotary motion transmitted from them to the discs I3I, the Xmarks upon the discs I3I will besuccessively brought into ,55

position for display through the sight opening I09. The X mark appearingthrough the sight opening indicates that the month below it is the oneunder consideration and the number appearing upon the disc I2! underthis month will indicate the date of the month under consideration. Bythis arrangement, the machine may be set to cause the X mark to appearover the month during which the note was signed and the day of thismonth upon which the note was signed will appear through the sightopening H0. The crank 7 may then be turned to rotate the shaft 4 androtary motion will be transmitted through the gears EM and H3 to theshaft H2 and the discs 12! and 13! will be turned, as previously setforth, until the X mark of the month in which payment is to be madeappears through the sight opening I09 and the disc [2! opposite thisdisc 131 discloses the correct date through the sight opening H0.

The manner of operating this calculating machine is as follows:

The first step is to turn the handle '5 until .00164 appears upon thesix percent interest unit through the window 29 and .00082 of the threepercent interest unit is seen through the window 28. Note that when themachine is cleared, the day counter always shows one day in the window80", this being for the reason that interest begins on the date a noteis signed and, therefore, in clearing the machine it has to be clearedas of one day.

In order to clear the machine, it is necessary to press down the leverl! and while holding this lever in a depressed position, turn the knob82 until the wheels of the day counter show 001 through the window 80.Concurrently the three percent interest unit will show .00082 throughthe window 28 and the percent interest unit shows .00164 through thewindow 29. Wh le in this position, it is necessary to release the lever|0| which is returned to its initial position by the spring E03 and itstooth i0 3 engages the ratchet I05 to prevent rotation thereof and placethe machine in condition for the succeeding operations. Next, set thestarting date of the note or other interest bearing paper by turning theknob 20 to effect rotation of the wheels or discs IZI and !3I, duringwhich time the discs iSi are successively turned to move their X marksinto position to be seen through the sight opening or window 09 and thecompanion discs l2] are turned to disclose, through the window H0,numbers representing days of the month. Assuming that the note is datedMarch 5th, the knob I 20 will be turned until an X mark appears throughthe window 100 over the word March upon the face plate and the number 5shows through the window H0 under the month of March. After setting thestarting date as of March 5th, the handle "I is turned until the datethe note is payable is reached, and assum ing that the note is due onMay 12th, the handle will be turned until the X mark appears over theword May and the number 12 shows through the window H0 under this month.At this point the day counter will show 00 through the window 30 toindicate the number of days which have elapsed. The three percentinterest unit now shows 0.5671 through the window 28 and by lookingthrough the window 20, it will be seen that the six percent interestunit shows 1.1343. These figures are the interest upon one hundreddollars for the elapsed time and are to be multiplied by the amount ofthe note. Assuming that the note is for $300 and the rate of interest is6%, 1.1343 showing through the window 29 will be multiplied by 3.00 upona calculating machine of a conventional construction and the result willbe 3.402900. Therefore, the interest due on a note for $300 at 6% is$3.40 for a period of 69 days.

As previously explained, this machine only gives a basic figure for anyrate of interest for any number of days up to the capacity of themachine. After obtaining the basic figure, this figure is then to bemultiplied by the amount of the principal on any calculator which willgive the total interest for the principal and by adding this to theprincipal the total amount to be paid will be obtained. Any calculatingmachine of a conventional construction which will multiply may be usedfor obtaining the total interest and any calculating machine of aconventional construction which will add may be used for adding theinterest to the principal and obtaining the total sum to be paid.

In addition to the day counter being used to count the intervening daysbetween any given dates, the day counter can also be used to inserttherein any predetermined amount of money by the turning of crank I(Figure 1) until such amount appears in window 80 Concurrently with theturning in of any sum of money, certain figures will appear in theinterest windows 20 and 29. These figures are then to be multiplied bythe number of days the note runs.

Example.--After the machine is cleared, suppose we have a note for$1,800.00 that ran thirty days at 6% interest. Turn crank '1 until 18appears in day counter window 80 (Figure 1). Concurrently with theturning in of this number the number .02959 will appear in the 6% window29. All that is necessary is to then multiply the number .02959 bythirty days, the running time of the note, and the result will co thecorrect amount of interest due after properly placing the decimal point.30 times .02959 equals 88770 and by pointing off four decimal points theresult is $8.87 the correct amount of intcLest due.

In addition the figure 18 appearing in the day counter window 80 willalso represent $1.80 or $18.00 or $180.00 or $1,800.00 or $18,000.00 or$180,000.00, etc. It only requires the correct placing of the decimalpoint in the answer to give the correct amount of interest due.

Having thus described the invention, what is claimed as new is:

1. In an interest calculating machine, a rotary drive shaft, and a datefinding unit eompr .Eng a frame, a face plate formed with spaced sightopenings, the names of months of a year being provided upon the faceplate between the sight openings, sets of companion discs rotatablymounted in said frame in position for display through the sight openingswith the name of a month between discs of each set, a month identifyingmark being provided upon one disc of each set and the other disc havingnumerals for indicating days of the month, means for transmitting rotarymotion from said drive shaft to the day indicating discs, and means forintermittently transmitting rotary motion from the day indicating discsto the companion month identifying discs.

2. In an interest calculating machine, a rotary drive shaft, and a datefinding unit comprising a frame, a face plate formed with spaced sightopenings, the names of months of a year being provided upon the faceplate between the sight openings,v sets of companion discs rotat ablymounted in said frame in position for display through the sightopeningswith the name of a month between discs of each set, a monthidentifying mark being provided upon one disc of each set and the otherdisc having numerals a drive shaft, and a date finding unit comprising afor indicating days of the month, the month identifying marks beingdisposed in a spiral path whereby the marks of adjoining discssuccessively move into position to be seen through the sight opening,means for rotating the day indicating discs from the main shaft, andmeans for intermittently transmitting rotary motion from the dayindicating discs to the companion month identifying discs. 7

3. In an interest calculating machine, a rotary drive shaft, and a datefindingunit comprising a frame, a face plate formed with spaced'sight'openings, the names of months of a year being provided upon the faceplate between the sight openings, a shaft rotatably mounted under onesight opening, a bank of day indicating discs and companion gearssecured to each other and rotatable with said shaft, a ratchet atone endof the bank fixed to the shaft, a gear wheel loose on said shaft, a pawlcarried by the gear wheel and engaging said ratchet, means for rotatingthe shaft to initially set the discs,;a gear carried by the main shaftand meshing with the gear wheel of the last mentioned shaft to rotatethe bank of day identifying discs and gears during operation. of theunit, a shaft under the second 4. In an interest calculating machine, arotary frame, a face plate formed with spaced sight openings, the namesof months of a year being provided upon the face plate between the sightopenings, a shaft rotatably mounted under one sight opening, a bank ofday indicating discs and companion gears secured to each other and ro-'ta-tab le with said shaft, a ratchet at one end of the bank fixed to theshaft, a gear wheel loose on said shaft, a pawl carried by the gearwheel and engaging said ratchet, means for rotating the shaft toinitially set the discs, a gear carried by the main shaft and meshingwith the gear wheel of the last mentioned shaft to rotate the bank ofday identifying discs and gears during operation of the unit, a shaftunder the second sight opening, month identifying discs and companiongears rotatably carried by the last mentioned shaft, Geneva wheelsrotatably mount ed and having gears fixed'thereto and meshing with gearsof the month identifying discs, and

gears meshing with the gears of the day identifying discs and havingfingers fixed at their sides and adapted to engage the Geneva wheels tointermittently rotate the Geneva wheels.

I ELBERT L. TURNBAUGH.

